Down Forward attack is the Blue Lunge attack, though I can understand you being confused.

DFA is the Red attack where the player leaps into the air with saber outstretced and lands in an area infront of him, with the saber in the ground. Its typically a 1 hit kill, but slow to use and slow to land.

The manual lists it as Foward+Attack+Jump which really really does not work.

To use it, tap your primary fire button to start a heavy swing, then as the swing is nearing completition, hold down your primary fire button and jump foward. U must be holding down your fire button.